(CBS/AP) David Kwiatkowski, a former technician accused of infecting 30 patients with hepatitis C at a New Hampshire hospital, denies taking or selling drugs.

Kiwatkowski, 33, stands accused of stealing syringes containing the powerful anesthetic Fentanyl from the hospital's cardiac catheterization lab where he worked, then refilling the syringes with another liquid and putting them back, enabling them to be used on patients.

He was arrested Thursday morning at a Massachusetts hospital where he was receiving treatment. Once he is well enough to be released, he will be transferred to New Hampshire to face federal drug charges, said U.S. Attorney John Kacavas.

"The evidence gathered to date points irrefutably to Kwiatkowski as the source of the hepatitis C outbreak at Exeter Hospital," Kacavas said in an FBI statement. "With his arrest, we have eliminated the menace this 'serial infector' posed to public health and safety."

Authorities in at least six states are investigating whether Kwiatkowski, who was a traveling hospital technician, also exposed earlier patients to the liver-destroying disease.

When asked how patients at Exeter contracted it, he said, "You know, I'm more concerned about myself, my own well-being."

Hepatitis C is a blood-borne viral infection that can cause liver disease and chronic health issues.

An FBI affidavit said Kwiatkowsi told police on July 2 he first became aware of his own hepatitis C diagnosis in May. Kacavas, however, said here is evidence Kwiatkowski had the liver-destroying disease since at least at least June 2010.

The FBI said in a press release that the charges against the former hospital employee relate to suspected thefts of the controlled substance Fentanyl, "a powerful anesthetic that is substantially more potent than morphine."

Fentanyl is a synthetic opiate used to treat patients with severe pain or manage pain following surgery, according to the National Institute on Drug Abuse. Similar to opioids such as heroin and morphine, the drug binds to the receptors in the brain to produce a state of euphoria and relaxation. The NIDA says some users amplify the drug's potency by mixing it with street-sold heroin or cocaine.

Kwiatkowsi said he is "not a shooter" and he is scared of needles.

"I did not take any drugs or do any drugs ... and I'm gonna stick to that," he told investigators. When he was told that a syringe bearing a fentanyl label was found in a bag in his vehicle, he said it was not his and suggested that it had been planted by a co-worker.

According to the affidavit, Kwiatkowski was observed at times leaving the lab sweating profusely and attending procedures on his off days. One witness said he appeared to be "on something." At least once, he was sent home for the day after a colleague told a supervisor that he was unfit to perform medical care, Kacavas said.

Kwiatkowski also said he "fabricated my life," saying two of the biggest lies he had told were claiming he played baseball at the University of Michigan and that his fiancée had died.

Originally from Michigan, Kwiatkowski worked at Exeter's cardiac catheterization lab from April 2011 through this past May, when he was fired.

Though state and local health departments aren't required to report such outbreaks to the Centers for Disease Control and Prevention, in a report released in June, the agency said it was notified of 13 outbreaks nationwide between 2008 and 2011. Of those, seven occurred in outpatient facilities; most were traced to unsafe injection practices.

At least two have resulted in criminal charges, however, including a Colorado woman who was convicted of stealing syringes filled with painkillers from two hospitals where she worked and replacing them with used syringes. The syringes were later used on surgical patients, and up to three dozen patients were found to have hepatitis C after being exposed.

Kacavas said New Hampshire is working with the federal Centers for Disease Control and Prevention, law enforcement and departments of public health in other states where Kwiatkowski worked.

"I'm unaware of such a scheme with such reach," he said. "This one has the potential for very far-reaching implications."

The New Hampshire Department of Health and Human Services, which had been investigating the outbreak since late May, said in an emailed statement to CBS News that it had identified drug diversion as the likely cause of the outbreak early in the investigation.

"This investigation has taken many turns and is still an on-going investigation," said N.H. Public Health Director Dr. Jose Montero. "We know that this healthcare worker was employed as a "traveler," working through an agency in healthcare facilities on temporary assignments. We've been coordinating efforts with the other states where this healthcare worker previously worked and the CDC."

In a statement, Exeter Hospital said he underwent drug testing and a criminal background check when he was hired.

"It is deeply disturbing that the alleged callous acts of one individual can have such an impact on so many innocent lives. As a result of his alleged actions, people in our community, who in many cases are the friends and neighbors of the 2,300 people who work here, now face the challenge of a potentially chronic disease," said Kevin Callahan, president and CEO of Exeter Hospital.

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